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DTC U0198: Lost Communication with Telematic Control Module: Procedure

  1. CHECK HARNESS AND CONNECTOR (COMMUNICATION LINE) 
    1. Disconnect the P2 and P5 ECU connectors.
      Fig 1: Identifying P2 And P5 ECU Connector End View Terminal
      GTY116760Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      P2-23 (MPX1) - P5-5 (S1) Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (TELEPHONE ECU ASSEMBLY - VEHICLE BATTERY AND BODY GROUND) 
    1. Disconnect the P2 ECU connector.
      Fig 2: Identifying P2 ECU Connector End View Terminal
      GTY144095Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage and resistance according to the value(s) in the table below.

      Standard Voltage

      Standard Resistance 

      Tester Connection Condition Specified Condition
      P2-1 (+B) - Body ground Always 11 to 14 V
      Tester Connection Condition Specified Condition
      P2-12 (E) - Body ground Always Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. REPLACE TELEPHONE ECU ASSEMBLY TOGETHER WITH MAYDAY BATTERY 

    NEXT → See step   4 

  4. PERFORM REGISTRATION. Refer to  REGISTRATION 
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